Extruder and continuous mixer arrangement for producing an at least partially baked product having a cookie-like crumb structure, the extruder including a microwave applicator

ABSTRACT

An extruder and continuous mixing appartatus operating to continuously mix, at least partially bake and extrude a preselected formulation of ingredients to provide an at least partially baked output product which, upon final baking, exhibits a cookie-like crumb structure with structural integrity. The extruder includes at least one screw-type element which is rotatably arranged in the extruder to vigorously mix and convey at least certain ingredients of the preselected formulation, including flour and oil, input through a feed port means at the upstream end of the extruder, wherein the total water content, by weight, of the ingredients is less than a preselected amount. A temperature control means operates to heat treat the ingredients during the vigorous mixing and conveyance by the screw-type element. The vigorous mixing and heat treatment is applied to the ingredients for substantially the entire length of the extruder. A microwave applicator is arranged at the downstream end of the extruder for further heat treatment of the ingredients. A continuous mixing apparatus is coupled to an output of the extruder to receive the heat treated ingredients at an upstream inlet. A source of water is coupled to the upstream inlet of the continuous mixing apparatus to add a preselected amount of water to the heat treated ingredients to increase the water content and modify the consistency of the ingredients after heat treatment and vigorous mixing and conveying. The continuous mixing apparatus is arranged for a gentle mixing and conveyance of the heat treated ingredients and added water.

This application is a continuation, of application Ser. No. 362,374,filed June 7, 1989, abandoned.

FIELD OF INVENTION

The present invention is directed to an apparatus for continuouslyproducing an at least partially baked product having a cookie-like crumbstructure and, more particularly, to a two stage mixing apparatusincluding, for example, an extruder including a microwave applicator anda continuous mixer operating together to at least partially bake,continuously mix and extrude a preselected formulation of ingredients toprovide an at least partially baked output product which, upon finalbaking, exhibits a cookie-like crumb structure.

BACKGROUND OF THE INVENTION

An extruder generally comprises a screw-like element rotably mountedwithin a bore or screw channel formed in a longitudinally extendedextruder barrel. The screw-like element includes various threadconfigurations which may alternate with mixing projections of variousshapes and sizes such that the rotation of the screw-like elementconveys and mixes ingredients which are fed into the screw channelthrough an inlet port arranged at the upstream end of the extruderbarrel. Typically, an extrusion port or die is mounted at the downstreammost end of the extruder barrel whereby the ingredients which have beenmixed and conveyed by the rotating screw-like element are forced throughthe die to provide an output product which comprises a thorough mixtureof the ingredients fed through the inlet port of the extruder.

In one advantageous embodiment of an extruder, twin screws are arrangedwithin side-by-side, communicating bores which have a figure eightcross-section. The screw threads and mixing projections of the twinscrews intermesh with one another in a self-cleaning action to mix,convey and otherwise mechanically work the various ingredients fed intothe inlet port. The dimensions of the communicating bores and elementsof the twin screws, as well as the speed of rotation of the twin screwscan be designed such that the operation of the extruder introduces highcompressive and shearing forces to the ingredients being mixed andconveyed throughout certain sections of the extruder to raise thetemperature and thereby heat treat the ingredients during theirconveyance through the extruder.

The heat treatment operation of an extruder also depends upon theviscosity of the mixed ingredients being conveyed. Generally, theviscosity must be high enough so that the viscous resistance of themixture to the shearing and compressive forces introduced by thescrew-like element results in sufficient friction to raise thetemperature of the mixed ingredients. An extruder may also include asupplemental heat source, such as an electric heater in each barrelsection arranged to surround the screw channel, to introduce heat, asfor example, by conduction into the ingredients. Such a supplementalheat source could be used when the viscosity of the mixture is not highenough to provide the friction required for heat treatment. The barrelof the extruder may also include tubing for the circulation of, e.g.,hot or cold water for additional temperature control of the screwchannel. Moreover, a thermostat control can be used to maintainpreselected temperatures at certain longitudinal sections or zones ofthe extruder. The thermostat may, for example, activate the electricheater to raise the temperature when the temperature level of a zonefalls below the preselected level and further activate a source ofcooling water through the tubing when the temperature level in the zonerises above the preselected level.

Extruders, particularly twin screw extruders, have been used widely inthe food industry to continuously mix ingredients to produce a raw doughand also to at least partially cook the ingredients, as they are mixed,to produce a partially or fully cooked food product. Typically,extruders are used to produce cereals, snacks, pet foods and otherproducts which generally are expanded upon extrusion through a die andwhich have relatively low amounts of oil as a percentage of the totalweight of the food product. It has been found, for example, that thepresence of oils above certain levels causes processing problems such assurging and product characteristics such as oil separation, which areundesirable. More specifically, upon extrusion, separated oil may appearas a coating on the remaining dough mass or periodically dischargeseparately from the remaining dough mass. Oil separation may be causedor aggravated by high pressure areas within the extruder as, forexample, at the extruder die and within high compressive force zones ina heat treatment section of the extruder. In such areas, the compressiveforces literally squeeze the oil from the dough mass.

In particular, it has been found that the use of an extruder to at leastpartially bake a cookie dough, which typically comprises a formulationincluding flour, added water and high amounts of both oil andcrystalline sugar, may result in oil separation and excessivedissolution of the crystalline sugar. Traditionally, a baked cookieexhibits a crumb structure having structural integrity (i.e. the productdoes not readily crumble apart). A crumb structure is a significantcharacteristic which affects the texture of a cookie product. Oilseparation caused by the high pressure, high temperature and/orturbulent conditions generated by the extruder, as required to achievethorough mixing and heat treatment of a product within the extruder,tends to preclude a crumb structure. Moreover, the presence of highamounts of both oil and crystalline sugar with water above a certainlevel promotes the dissolution of the sugar in the water to increase therelative amount of hydrophilic mass which in turn, tends to causefurther oil separation. The dissolved sugar may also result in anexcessively hard texture for the final product. For these reasons,extruders have not been heretofore successfully utilized to at leastpartially bake a cookie dough to produce a final product having acookie-crumb-like structure with structural integrity.

Conventional cookie production involves forming a cookie dough which iscut into pieces followed by baking of the pieces. Low temperatures,typically at about room temperature, are used to form the dough in abatch process. The low temperature mixing generally avoids separation ofoil from hydrophilic dough components. While baking temperatures in aconventional oven, such as a band oven, may promote oil separation,there is no mixing or pressing action performed at the bakingtemperatures, as occurs in an extruder, to squeeze the oil from thedough mass. Any oil separation which may occur in such ovens does notgenerally interfere with continuous operability of the cookie productionprocess as it would in a continuous cooker/extruder process.

SUMMARY OF THE INVENTION

It is a primary objective of the present invention to provide anextruder apparatus which is operable in accordance with a novel processas disclosed in copending U.S. Application entitled "Cookie ProductionWith Extrusion, Heat Treatment and Post Extrusion Mixing and Baking",filed on even date herewith, which is hereby expressly incorporated byreference. The process of the co-pending patent is directed to a processto continuously mix and at least partially bake the ingredients of adough formulation to produce a partially baked output product which,when fully baked, has a cookie-crumb-like structure with structuralintegrity. Generally, the apparatus of the invention comprises ascrew-type extruder, preferably a twin screw extruder, having upstreamingredient inlet ports and a second stage mixing device, such as acontinuous mixer, coupled to the downstream end of the extruder.Moreover, a microwave applicator is provided at the downstream end ofthe extruder for heat treatment of indgredients flowing in the exturderprior to input into the second stage mixing device. The screwconfiguration of the extruder comprises a novel sequence of conveying,mixing and kneading elements arranged relative to the upstream inletports so that ingredients comprising flour and oil can be input throughthe upstream inlet ports, conveyed and mixed under conditions to elevatethe temperature for heat treatment to partially bake the ingredientscomprising flour and oil within the extruder by the barrel sections andthe action of screw elements, preferably for substantially the entirelength of the extruder. Moreover, the microwave applicator is formed atthe downstream most end of the extruder to provide additional heattreatment to the ingredients.

The partial baking by the extruder of the ingredients comprising flourand oil input through the upstream inlet ports of the extruder with anelimination or significant reduction of added water or a source of addedwater at the upstream end of the extruder results in a reduction in oilseparation from the mass of flour and oil which is sufficient toeliminate surging in the extruder and undesirable productcharacteristics such as a surface layer of oil on the extruded doughmass. The extruder is generally operated at relatively low pressure tofurther minimize oil separation.

The viscosity of an oil and flour formulation when admixed in a extruderwith a minimal amount or no added water, is too low for viscousresistance heat treatment processing. Generally, if the amount of addedwater is too low, the extrudate will tend to be a slurry-like mass whichis not suitable for friction heat treatment within the extruder or forshaping and cutting in post extrusion processing. Thus, a supplementalheat source is used to heat treat the ingredients comprising oil andflour while the screw configuration is designed for vigorous mixing andincreasing degree of fill within the free volume of the screw channel toprovide an even heat distribution throughout the thoroughly mixedingredients preferably for substantially the entire length of theextruder.

When added water or a source of added water is provided in theextrudate, the consistency can be modified to provide a mixture havingsufficient formability and machinability for shaping and cutting into afinal product. As the amount of added water is increased, the extrudateconsistency changes to a dough-like elastic mass until a threshold levelis reached. At this level, additional water reduces the consistency andfurther addition of water may result in substantial oil separation andextruder surging.

The introduction of added water in amounts below the threshold levelresults in the added water mixing with glutens in the flour to provide amass with elastic properties which is hydrophilic in nature. The elastichydrophilic mass, while improving the formability and machinability ofthe formulation, will increase the tendency toward oil separation undercertain temperature and pressure conditions.

Consistencies suitable for forming or cutting operations depend upon theparticular operation and particular equipment utilized. For example, aconsistency which is too high for wire cutting may be suitable forsheeting or rotary molding. For rotary molding, the consistency at aboutthe threshold level is suitable. For extrusion through a die, forproducing a sheet for example, or for wire cutting, the consistencyshould be less than the threshold value. However, to reduce the risk ofsubstantial oil separation in the extruder or in post extrusion formingoperations and to reduce post extrusion baking times, it is generallypreferred that the amount of water added be less than the amount neededto reach the threshold or maximum consistency. Thus, it is generallypreferred that the water content of the dough-like mixture is such thatany additional water would further increase the consistency of thedough-like mixture.

If the ratios of the amounts of the other ingredients are kept constantthen: the amount of water added which is needed to reach the thresholdlevel of consistency will depend upon the heat treatment of theingredients. Generally, the longer the heating, or the higher thetemperature of heating, the lower is the amount o water needed to reachthe threshold level of consistency.

The heat treated mass temperature before and/or during admixing withwater or a source of water should be sufficiently low so that the addedwater does not result in substantial separation of oil and extrudersurging. The reduction of the temperature of the heat treated masssubstantially reduces mobility and immiscibility of the water and oilphases. Also, it has been observed that the oil is most likely toseparate from the remaining mass at the points of highest pressure, suchas at the extruder die. Generally, the lower the pressures encounteredby the heat treated mass upon or subsequent to the addition of thewater, the less the heat treated mass needs to be cooled to avoidsubstantial oil separation and extruder surging.

If pressures are sufficiently low (such as when an extruder die is notutilized) and if the mass temperature during heat treatment issufficiently low, little or substantially no cooling may be needed toavoid substantial oil separation or extruder surging. However, higherheat treated mass temperatures are preferred for: (1) the promotion ofbrowning and flavor development, and (2) reduced post extrusion heatingtimes. Thus, it is generally preferred that the heat treated mass beheated to a high temperature and that the heat treated mass temperaturebe reduced before and/or during admixing it with water or source ofwater. Cooling of the heat treated mass is preferably initiated prior toand continues during admixing it with water or a liquid source of waterto reduce the risk of substantial oil separation upon mixing orextrusion.

Accordingly, at least a substantial portion of the added water is addedat an added water inlet arranged in the second stage mixing device formixing with the partially baked ingredients comprising flour and oilwhich are extruded from the extruder and fed directly into a dryingredient inlet port of the second stage mixing device. The secondstage mixing device may comprise a continuous mixer which is similar inconstruction to an extruder except that, for the same screw diameter, acontinuous mixer has a greater free volume and operates to mix andconvey ingredients at relatively lower pressures and shear than anextruder to obtain a substantially homogenous output. An extruder canalso be used as the second stage mixing device if operated at lowtemperature and low pressure.

An extruder is preferable as the second stage mixing device when apressure build up is required for shaping, as for example, through anextrusion die. The extruder also permits an axial exit of the extrudatefor unidirectional continuous processing. On the other hand, in a highvolume production environment, a continuous mixer is preferred toprovide a higher volumetric through put and a better heat transfer fromthe ingredients for efficient and rapid cooling. A continuous mixer alsopermits a more efficacious particulate feeding.

A thorough yet gentle mixing by the second stage mixing device of theadded water throughout the heat-treated mass at relatively lowtemperature enables the added water to be dispersed throughout the othercookie ingredients and to modify the consistency of the mass to providean output product from the second stage mixing apparatus suitable forshaping and cutting. Unacceptable oil separation is avoided due to therelatively low water addition, low temperature and low pressureoperation of the second stage mixing device. Crystalline sugar is addedupstream through the extruder input port and/or downstream at the inputport of the second stage mixing device.

The relative amount of at least one crystalline sugar or granulatedsugar, such as sucrose, which is input through the extruder inlet portwith the flour and oil and subjected to the heat treatment, is used tocontrol the tenderness and crunchiness of the final product. Morespecifically, the addition of a portion of the crystalline sugar to theflour and oil formulation through the extruder inlet port with the addedwater input through the inlet port of the second stage mixing device, tominimize the dissolution of sugar, tends to promote a crunchy texture tothe crumb structure of the final product. Addition of all or a portionof the crystalline sugar through the inlet port of the second stagemixing device, which operates at lower temperature and lower pressurethan the first stage extruder, tends to avoid excessive sugardissolution and promotes a tender texture in the final product. Pursuantto the process of the co-pending application, 15%-85% of the totalcrystalline sugar is added through the extruder inlet port and 15%-85%of the total crystalline sugar is added through the inlet port of thesecond stage mixing device depending upon the desired crunchiness of thefinal product.

Moreover, a downstream input of all or a portion of the crystallinesugar through the inlet port of the second stage mixing device reducesthe total mass which must be heat-treated by the extruder andfacilitates the cooling of the heat-treated mass by adding therelatively cool bulk of the crystalline sugar at the inlet port of thesecond stage mixing device, the second stage mixing device beingoperated at lower temperatures.

In this manner, the added water and all or a portion of the crystallinesugar is added to the formulation subsequent to the heat treatment ofthe other ingredients so that the water does not modify the consistencyof the heat treated mass until after the high temperatures of the heattreatment provided by the extruder and, therefore, the extrudate is notexposed to conditions which can cause oil separation or excessivedissolution of the crystalline sugar in the water. This promotes a crumbstructure in the final product which is either tender or crunchy,depending upon the level of upstream crystalline sugar addition, but notexcessively hard.

The use of substantially the entire maximum available length of theextruder to heat treat the ingredients comprising oil, flour andoptionally, the upstream added crystalline sugar permits significantdevelopment of Maillard reaction promoters, and flavor promoters andfurther substantially reduces the amount of post extrusion heattreatment required for final baking of the output product. Thetemperature of the heat treatment zone is preferably as high as possiblefor a given throughput rate without deleterious effects on theingredients. The separation of the heat treatment zone of the firststage extruder from the low temperature operation of the second stagemixing apparatus also eliminates the loss of heat by conduction throughthe screw shafts and the screw elements inasmuch as the screw shafts ofthe first and second mixing stages are physically separate from oneanother. The microwave applicator provides additional heat treatment tothe indregients fed into the extruder to thereby further reduce theamount of post extrusion heat treatment required for final baking of theoutput product.

The output product from the second stage mixing device is a partiallybaked, homogenous cookie dough-like mass including added water andcrystalline sugar without excessive dissolution of the added crystallinesugar and with a sufficient total water content for forming and shaping.The second stage mixing device, according to the invention, is operatedsuch that the temperature and/or pressure acting upon the food productnear the output of the continuous mixer, is sufficiently low so as toprevent oil separation or a flash off of moisture and thereby limitexpansion of the product at the output of the continuous mixer. Thus,the cookie-dough-like product output does not crumble apart and remainsdough-like in consistency for shaping, cutting and further processingbefore final baking. The minimal amount of final baking required due tothe preferred use of the entire length of the extruder for heattreatment and the further use of the microwave applicator permits theaddition of heat sensitive or particulate ingredients to theformulation, for example, through a downstream feed port in thecontinuous mixer.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side view of an extruder including a microwave applicatorand continuous mixer of the present invention.

FIG. 2 is an end cross-section of the extruder taken along line 2--2 ofFIG. 1.

FIG. 2a is a cross-section of the microwave applicator taken along line2a--2a of FIG. 1.

FIG. 3 is a top view, partially broken away of the extruder and secondstage mixing device of FIG. 1.

FIG. 4 is a schematic representation of the screw configuration of theextruder of FIG. 1.

FIG. 5 is a schematic representation of the screw configuration of thesecond stage mixing device of FIG. 1 wherein the second stage mixingdevice comprises an extruder.

FIG. 6 is a schematic representation of an alternative screwconfiguration for the extruder of FIG. 1.

FIG. 7 is a schematic representation of the screw configuration of thesecond stage mixing device of FIG. 1 wherein the second stage mixingdevice comprises a continuous mixer.

DETAILED DESCRIPTION

Referring now to the drawings and initially to FIG. 1, there isillustrated a side view of an extruder 10 and second stage mixing device100 arranged according to the present invention. The extruder 10comprises a plurality of barrel sections, e.g., twelve barrel sections11-22, (see FIG. 4) each of which includes a figure eight cross-sectionbore or screw channel 23 formed therethrough (see FIG. 2). The sections11-22 are fastened end-to-end, to one another with the respective boresections 23 axially aligned, as is well known, to provide the screwbarrel of the extruder 10. A dry ingredient feed port 30 is provided inbarrel section 11 for input of, for example, flour and a liquid feed 32is arranged between barrel sections 11 and 12 for input of oil.

The downstream most end of the extruder is formed as a microwaveapplicator 201, as will be described in further detail below.

The output end 80 of the extruder 10 is aligned above an inlet feed port101 of the second stage mixing device 100. Thus, the heat treatedingredients output by the extruder 10 are fed, together with addedwater, input through a water inlet port 200, directly into the secondstage mixing device 100.

Twin screws 24, 25 can be arranged in the extruder 10 in an intermeshingarrangement, to extend through communicating screw channels 26, 27 ofthe figure eight cross-section bore 23 from one end of the extruderbarrel formed by the barrel sections to the other end thereof. The twinscrews 24, 25 are coupled to an electric motor 28, arranged adjacent theupstream end of the extruder 10 for rotation within the screw channels26, 27.

As illustrated in FIG. 1, the extruder 10 is divided into a blendingzone and a mixing and heat treatment zone. The mixing and heat treatmentzone is preferably arranged to extend along a substantial portion of thelength of the extruder 10. In addition, the microwave applicator 201 isformed as a continuation of the screw channel 23 at the downstream mostend of the extruder 10.

Referring now to FIG. 4, there is illustrated, in schematic form, aspecific screw configuration for each of the twin screws 24, 25 of theextruder 10. The illustrated screw configuration is now described as arepresentative embodiment of the present invention. Each of the screws24, 25 comprises a series of elements intermeshing with an adjacentidentical series of elements of the other screw 24, 25. Screw elements34, 35, the upstream most elements, are arranged directly beneath thedry ingredient feed port 30. The screw elements 34, 35 each include acontinuous screw-like thread 36 to rapidly convey dry ingredients suchas flour and a portion of the crystalline sugar into the screw channel23. Each of the elements 34, 35 comprises an 80/80/SK screw elementwhich indicates that the screw-like thread has a pitch of 80 and thateach element is 80 mm in length. The SK designation indicates a shufflekneader which includes undercut threads to catch and carry dryingredients as they are input through the dry ingredient feed port 30.The liquid feed port 32 is arranged adjacent the dry ingredient feedport 30 for input of oil. The screw elements 34, 35 generally comprisethe blending zone of the extruder 10.

A screw element 37 is arranged immediately downstream from the 80/80/SKelements 34, 35 and comprises an 80/40 screw element (i.e. a pitch of 80and a length of 40 mm). The screw element 37 is followed immediately bya 60/60 screw element 38 and a 40/40 screw element 39. The progressivelyshorter, lower pitch screw elements 37, 38, 39 decrease the speed ofconveyance to thereby increase the degree of fill of the ingredientswithin the free volume of the bore 23. Degree of fill refers to thepercentage of the free volume of the bore 23 occupied by ingredientsbeing conveyed by the screw elements 24, 25.

An igel element 40, which is 40 mm in length, is arranged immediatelydownstream from the screw element 39. An igel element includes churningprojections 41 to provide a chopping action to the ingredients withinthe bore 23. The igel element 40 does not itself convey material whichcauses a further increase in the degree of fill. The through put flow ofingredients through the igel element 40 is caused by the pushing actionon the ingredients by the screw elements 34, 35, 37, 38 and 39 upstreamfrom the igel element 40.

Two 40/40 screw elements 42, 43 are arranged immediately downstream fromthe igel element 40 to continue the conveyance of the ingredients. Twoadditional 40 mm igel elements 44, 45 are provided downstream from thescrew element 43. These igel element elements 44, 45 are spaced from oneanother by a 40/40 screw element 46. Moreover, an additional 40/40 screwelement 47 is arranged immediately downstream from the igel element 45.The igel element elements 44, 45 and screw elements 46, 47 therebyprovide alternating elements to chop, convey, chop and convey theingredients. This sequence gradually increases the degree of fill anchurns the ingredients to afford a better mixing of the ingredients.

A first kneading block element 48 is positioned directly downstream fromthe screw element 47. The kneading block element is used to mix theingredients and comprises a KB/45/5/20 element. This indicates that itis a kneading block having mixing discs staggered at 45° right handangles, relative to one another around the axis of rotation of thescrew, 5 total discs in the element and the element is 20 mm long.

The kneading element 48 is followed by a 40/40 screw element 49.Thereafter, there is an alternating sequence of kneading block elements50-56 and interposed screw elements 57-63. Each of the intermediatescrew elements 57-63 comprises a 40/40 screw element while the kneadingblock elements 50-56 comprise, in downstream order, a KB/45/5/20 element(kneading block 50), four KB/45/5/40 elements (kneading blocks 51-54)and two KB/45/5/60 elements (kneading blocks 55-56).

The gradual increase in size of the kneading block elements 50-56 andrelatively short, low pitch screw elements 57-63 in-between thesuccessive kneading block elements causes a continuing increase indegree of fill and a vigorous mixing of the ingredients.

Immediately downstream from the screw element 63 is a further series ofalternating kneading block elements 65-70 with interposed screw elements64 and 71-75. Each of the screw elements 64, 71-75 comprises a 60/60screw element and each of the kneading block elements 65-70 comprises aKB/45/5/60 kneading block element. This configuration of alternatingkneading block elements 65-70 further vigorously mix the ingredients.The alternating kneading element sequences defined by kneading element50-56 and 65-70 in barrel sections 14-21 provide a vigorous mixing zonethroughout a substantial portion of the length of the extruder.

Each of the barrel elements 11-22 includes an electrical heating element500 and cooling water flow tubing 501 to control the temperature of thebarrel element (see FIG. 2). Such a temperature controlled barrelelement comprises, for example, a model ZSK-57 extruder barrel elementmanufactured by Werner & Pfleiderer. The viscosity of the ingredientscomprising flour and oil is not sufficient for friction heating due tovigorous mixing action of the kneading block elements 50-56 and 65-70.Accordingly, the heating elements 500 of barrel elements 12-22 areoperated to raise the temperature of the ingredients. The electricalheating elements 500 of the barrel elements 12-22 are operated to raisethe temperature of the barrels to as high as possible, e.g. 350° F., fora given throughput rate to promote Maillard browning and flavordevelopment and to reduce the amount of post extrusion heat treatmentrequired for final baking.

The heated barrel sections 12-22 generally comprise the heat treatmentzone of the extruder 10. In this manner, substantially all of the lengthof the extruder 10 is used for vigorous mixing and heat treating theingredients comprising flour and oil fed through the inlet feed ports tothe extruder 10. Thus, the ingredients fed through the first dryingredient feed port 30 and first liquid feed port 32 are thoroughlymixed and heat-treated by the overall conveying, churning and mixingaction of the screws 24, 25 and heating effect of the barrel sections12-21. The term "vigorous" as used herein means a mixing action which issufficient to thoroughly mix the ingredients input through the first dryingredient feed port 30 including the flour, oil and, optionally,crystalline sugar, and to facilitate distribution of the heat applied bythe heating elements throughout the ingredients. In addition, the termrelates to increasing the degree of fill to a level accommodating heatconduction from the heating elements through the screw channel 23 andinto the ingredients.

Screw elements 76-79 are arranged downstream from the kneading blockelement 70 and comprise one 80/80 and three 60/60 elements,respectively, to increase the speed of conveyance and transport theingredients out the open end 80 of the extruder 10. The screw channel 23beyond the screw element 76-79 and within the microwave applicator 201is conformed to a round channel surrounded by a source of microwaveenergy 202 (see FIG. 2a). The source of microwave energy is operated toelevate the temperature of the ingredients within the extruder 10 to ashigh as possible for a given throughput rate, e.g. by as much as 200° F.The residence time of the ingredients within the microwave applicator isrelatively short, e.g. 5-20 seconds.

Referring now to FIG. 5, the second stage mixing device 100 comprises anextruder, which is about 12 l/d and includes four barrel sections102-105 fastened end-to-end with twin screws (screw 106 illustrated) ina similar manner as the extruder 10. A motor 150 (see FIG. 1) is coupledto the screws for rotation. Relatively high pitch screw elements107-109, e.g. 120/120 screw elements, are arranged directly below theinlet feed port 101 to rapidly convey the heat treated ingredientscomprising oil and flour from the extruder 10, and any added crystallinesugar downstream from feed port 101. The added water is input throughthe liquid feed port 200. As noted above, the added water modifies theconsistency of the mixture to provide an elastic mass having sufficientformability and machinability for post extrusion processing.

The screw elements 107-109 are followed by alternating kneading blocks110-112 with interposed screw elements 113-114. The screw elements113-114 are shorter and of lower pitch than the screw elements 107-109,e.g. 80/80 so that, together with the kneading blocks 110-112 (e.g.KB/45/5/80 elements), they act to lower the speed of conveyance andincrease the degree of fill to permit thorough mixing of the ingredientsby the kneading block elements 110-112 However, the number ofalternating kneading block elements is fewer than in the first extruder10 to provide a gentle lower temperature mixing to avoid oil separationafter the addition of the water. The barrel sections 102-105 of thesecond stage extruder include temperature control means (not shown)which are operated to maintain the barrel sections at lower temperaturesthan in the barrel sections of the heat treatment zone of the extruder10 to further prevent oil separation after water addition.

The alternating kneading blocks 110-112 are followed by three screwelements 115-117 of decreasing pitch and length (e.g. two 120/120element followed by an 80/80 element) to feed the ingredients into finalkneading block elements 118-119 (e.g. KB/45/5/100 elements) for finalmixing. A screw element 120 (e.g. a 120/60 element) is interposedbetween the kneading block elements 118, 119 and a final screw element121 (e.g. an 80/80 element) is arranged downstream from the kneadingblock elements 118, 119 to output the cookie dough from second stageextruder 100.

A second downstream inlet feed port 122 can be formed in barrel section104, above the screw elements 115, 116 for input of ingredients such asparticulate ingredients, e.g., nuts, chocolate chips etc. and/or heatsensitive ingredients. The screw elements 115-116 increase the speed ofconveyance of the ingredients below the second feed port 122, whichdecreases the degree of fill and facilitates the intake and mixing ofthe ingredients fed through the inlet port 122 by the kneading blockelements 118-119.

Referring now to FIG. 6, there is illustrated, in schematic form, analternative screw configuration for each of twin screws 24', 25' of theextruder 10. As in the embodiment of FIG. 4, each of the screws 24', 25'comprises a series of elements intermeshing with an adjacent identicalseries of elements of the other screw 24', 25'. Screw elements 34', 35',the upstream most elements, are arranged directly beneath the first dryingredient feed port 30'. The screw elements 34', 35' each include acontinuous screw-like thread 36' to rapidly convey dry ingredient suchas flour and a portion of the crystalline sugar into the screw channel23'. Each of the elements 34', 35' comprises an 80/80/SK screw element.The first liquid feed port 32' is arranged adjacent the first dryingredient feed port 30' for input of oil. The screw elements 34', 35'generally comprise the blending zone of the extruder.

A screw element 37' is arranged immediately downstream from the 80/80/SKelements 34', 35' and comprises an 80/40 screw element. The screwelement 37' is followed immediately by a 60/60 screw element 38' and a40/40 screw element 39'. The progressively shorter, lower pitch screwelements 37', 38', 39' decrease the speed of conveyance to therebyincrease the degree of fill of the input oil and flour ingredientswithin the bore 23'.

An igel element 40', which is 40 mm in length, is arranged immediatelydownstream from the screw element 39'. The igel element 40' includeschurning projections 41 to provide a chopping action to the ingredientswithin the bore 23'.

Two 40/40 screw elements 42', 43' are arranged immediately downstreamfrom the igel element 40' to continue the conveyance of the ingredients.Two additional 40 mm egel elements 44', 45' are provided downstream fromthe screw element 43'. These igel elements 44', 45' are spaced from oneanother by a 40/40 screw element 46'. Moreover, an additional 40/40screw element 47' is arranged immediately downstream from the igelelement 45'. The igel elements 44', 45' and screw elements 46', 47'thereby provide alternating elements to chop, convey, chop and conveythe ingredients. As in the screw configuration illustrated in FIG. 4,this sequence gradually increases the degree of fill and churns theingredients to afford a better mixing of the ingredients.

A first kneading block element 48' is positioned directly downstreamfrom the screw element 47'. The kneading block element is used to mixthe ingredients and comprises a KB/45/5/20 element.

The kneading element 48' is followed by a 40/40 screw element 49'.Thereafter, there is an alternating sequence of kneading block elements50'-56' and interposed screw elements 57'-63'. Each of the intermediatescrew elements 57'-63' comprises a 40/40 screw element while thekneading block elements 50'-56' comprise, in downstream order, aKB/45/5/20 element (kneading block 50'), four KB/45/5/40 elements(kneading blocks 51'-54') and two KB/45/5/60 elements (kneading blocks55'-56').

The gradual increase in size of the kneading block elements in size ofthe kneading block elements 50'-56' and relatively short, low pitchscrew elements 57'-63' in-between the successive kneading block elementscauses a continuing increase in degree of fill and a vigorous mixing ofthe ingredients. Thus, the kneading block elements 50'-56' in barrelsections 14'-17' comprise a vigorous mixing zone.

Each of the barrel elements 11'-22' includes heating elements 500 andcooling water flow tubing 501 as shown in FIG. 2 to control thetemperature of the barrel element. Such a temperature controlled barrelelement comprises, for example, a model ZSK-57 extruder barrel elementmanufactured by Werner & Pfleiderer. The electrical heating elements ofbarrel elements 12'-22' are operated to raise the temperature of theingredients. The heating elements of the barrel elements 12'-22' areoperated to raise the temperature of the barrels to as high as possible,e.g. at least 350° F., for a given throughput rate to promote Maillardbrowning and flavor development and to reduce the amount of postextrusion heat treatment required for final baking.

Thus, the ingredients fed through the first dry ingredient feed port 30'and first liquid feed port 32' are thoroughly mixed and heat-treated bythe overall conveying, churning and mixing action of the screws 24', 25'in barrel sections 14'-17' and the heating effect of the barrel sections12'-22'. The barrel sections 12'-22' generally comprise the heattreatment zone of the extruder 10 which extends throughout substantiallythe entire length of the extruder 10. The vigorous mixing occurs inbarrel sections 14'-17'.

Immediately downstream from the last screw element 63' of thealternating screw and kneading block elements is a conveyance zonecomprising a series of screw elements 64'-68' of generally increasinglength and screw pitch. The conveyance zone is for the optional additionof crystalline sugar into the heat treatment zone to control texture andcrunchiness of the final product. Thus, crystalline sugar can optionallybe added downstream from the feed port 30' to reduce the exposure of thesugar to full heat treatment as a further control over the crunchinessof the cookie texture. As illustrated in FIG. 6, the series of screwelements 64'-68' are located in barrel sections 17', 18' and 19'. Barrelsection 18' can include a feed port 31' which can be opened or closeddepending upon whether crystalline sugar is to be added into theconveyance zone.

The screw elements 64'-68' comprise 60/60, 80/80/SK, 80/80/SK, 80/40 and80/80 screw elements, respectively, which increases the speed ofconveyance of the heat treated ingredients.

Screw elements 69'-71' are arranged downstream from the screw elements64'-68' and comprise one 60/60 and two 30/30 elements, respectively, toreduce the speed of conveyance and again gradually increase the degreeof fill. A kneading block element 72', which comprises a KB/45/5/20element, is provided downstream from the screw elements 69'-71' tofurther mix the ingredients including any optional sugar fed into theconveyance zone defined by the screw elements 64'-68'.

Two additional screw elements 73', 74', which comprise a 40/40 and80/160 element, respectively, convey the ingredients to a final kneadingblock element 75', which comprises a KB/45/5/60 element for final mixingof the ingredients. The kneading block elements 72', 75' provide thefinal mixing zone of the extruder.

The final elements of the twin screws 24', 25' comprise screw elements76'-78', which include an 80/80, a 60/60 and a 60/120 element,respectively. These elements convey the ingredients to the inlet port ofthe second stage mixing device 100 through the microwave applicator 201in a manner similar to the embodiment of FIG. 4.

Referring now to FIG. 7, there is illustrated in schematic form, a screwconfiguration for a second stage mixing device 100 which comprises acontinuous mixer. The continuous mixer 100 includes three barrelsections 600-602 with the dry ingredient inlet port 101 and added waterfeed port 200 arranged in barrel section 600, the downstream inlet port122 in barrel section 602 and a vertical output opening 603 in barrelsection 602. The continuous mixer is a twin screw arrangement with oneof the two identical screws 604 illustrated in FIG. 7. Each of thescrews includes 21 elements as set forth in the following table:

    ______________________________________                                        Element    Length       Element                                               No. (FIG. 7)                                                                             (in mm)      Type                                                  ______________________________________                                        605        270          single lobe                                                                   conveying element                                     606        90           double lobe                                                                   conveying element                                     607        30           kneading disc                                         608        30           kneading disc-30°                                                      right hand staggered                                                          relative to kneading                                                          disc 607                                              609        30           kneading disc-30°                                                      right hand staggered                                                          relative to kneading                                                          disc 608                                              610        90           double lobe                                                                   conveying element                                     611        30           kneading disc                                         612        30           kneading disc-30°                                                      right hand staggered                                                          relative to kneading                                                          disc 611                                              613        30           kneading disc-30°                                                      right hand staggered                                                          relative to kneading                                                          disc 612                                              614        30           kneading disc-30°                                                      left hand staggered                                                           relative to kneading                                                          disc 613                                              615        30           kneading disc-30°                                                      left hand staggered                                                           relative to kneading                                                          disc 614                                              616        60           kneading disc with                                                            pitch (for conveying                                                          effect)-30° right                                                      hand staggered                                                                relative to kneading                                                          block 615                                             617        90           double lobe conveying                                                         element                                               618        90           double lobe conveying                                                         element                                               619        90           double lobe conveying                                                         element                                               620        60           kneading disc with                                                            pitch                                                 621        30           kneading disc-30°                                                      right hand staggered                                                          relative to element                                                           620                                                   622        30           kneading disc-30°                                                      right hand staggered                                                          relative to element                                                           621                                                   623        90           double lobe                                                                   conveying element                                     624        60           kneading disc                                                                 with pitch                                            625        60           kneading disc with                                                            pitch 30° right hand                                                   staggered relative to                                                         element 620                                           ______________________________________                                    

The single lobe screw element 605 rapidly conveys the heat treatedingredients comprising flour and oil from the extruder 10 together withand crystalline sugar input through the feed port 101 and the addedwater fed into the screw channel of the continuous mixer 100.

The various kneading discs 607-609, 611-616, and 621, 622 withintermediate double lobe conveying elements 606, 610, 617, 618, 619 and623 gently mix and convey the dough-like mass including added watertoward the vertical output opening 603. The left hand staggering ofkneading discs 614, 615 reduces the rate of conveying withn the kneadingdiscs 612-615 to increase the amount of mixing. The kneading discs withpitch 616, 620 both mix and convey the ingredients.

The downstream inlet port 122 is arranged above the screw elements 617,618 which provide a conveyance zone within the continuous mixer forrapid intake of particulate materials which may be input through theport 122.

The double lobe conveying element 623 is arranged partially above thevertical output opening 603 to convey the dough-like mass toward and outof the continuous mixer 100. The kneading discs with pitch 624, 625 tendto dump the ingredients fed by the double lobe screw element 623 out theopening 603.

The barrel sections 600-602 include cooling jackets for water flow. Acooling water flow is pumped through the jackets in barrel sections600-602 to reduce and adjust dough temperature during the gentle mixingand conveying of the dough-like mass by the continuous mixer.

The following table illustrates the basic ingredients for a cookie doughand representative and preferred ranges of each ingredient as apercentage of the total weight of the dough:

    ______________________________________                                                      Representative                                                  Ingredient    Range       Preferred Range                                     ______________________________________                                        Flour (about 12%                                                                            30%-70%     45%-55%                                             water by weight)                                                              Water (including                                                                            <20%        <15%                                                water content                                                                 of the flour)                                                                 Oil (shortening                                                                             12%-40%     15%-30%                                             or fat)                                                                       Sucrose       10%-40%     15%-30%                                             (crystalline sugar)                                                           ______________________________________                                    

As discussed above, the flour and oil are input through the dryingredient port 30 (or 30')and liquid feed 32 (or 32'), respectively, ofthe extruder 10, and are subject to vigorous mixing (in barrel sections14-21 (FIG. 4) or 14'-17' (FIG. 6)), heat treatment in barrel sections12-22 (or 12'-22') and microwave heat treatment in the microwaveapplicator 201. The added water, i.e., for example, from about 0.5%weight to about 10% weight of the total dough mix, is input through theliquid feed port 200 of the second stage mixing device 100. The totalwater of, e.g., <20% and preferably <15% by weight is therefore notprovided until after the vigorous mixing and heat treatment of theingredients comprising flour and oil to minimize oil separation. Theadded water input through the liquid feed port 200 is gently mixedgenerally at low temperatures with the heat treated ingredients in thesecond stage mixing device 100 to provide the dough mass consistencyrequired for forming and cutting.

The consistency of the extrudate can be determined by measuring theforce needed to penetrate a sample at a constant rate of penetration. AnInstron Texture Analyzer Model 4202 can be used to determine the modulusof the sample, which is a measurement of the consistency of the sample.The modulus is the slope, in the linear region, of a plot of the strainor deformation (x-axis) versus the stress (y-axis). The strain can bemeasured in inches and the stress can be measured in lbs force. Acylindrical shaped probe having a diameter of 4 mm can be used for themeasurement of the consistency. The probe can be set to penetrate thesample at a constant speed of 0.2 inches/min. The sample may comprise a1 inch square piece which is 1/4 inch thick and the sample temperaturecan be room temperature (about 70°-75° F.) or higher. The more forcerequired to penetrate the sample, the greater is its modulus and thegreater is its consistency.

The crystalline sugar is added either through the dry ingredient feedport 101 of the second stage mixing device 100 or partially through thedry ingredient feed port 101 of the second stage mixing device 100 andpartially through the dry ingredient feed port 30 of the extruder 10. Aportion of the upstream crystalline sugar can also be added through thefeed port 31' in barrel section 18' of the extruder illustrated in FIG.6. The ratio of upstream to downstream sugar addition is preferably 15%to 85% of the total crystalline sugar through each of the dry ingredientfeed ports 30, 101 (or 30', 31' and 101). The crystalline sugar added inthe extruder 10 is subjected to vigorous mixing and heat treatment andwill tend to provide a crunchy texture to the final product. The amountof crystalline sugar added to the extruder 10 will be a function of thedesired crunchiness of the final product. The upstream added crystallinesugar will not undergo excessive dissolution to provide a hard textureto the final product or contribute to oil separation during heattreatment processing because the total water of the mixture prior to theaddition of the added water in the second stage mixing device 100 is notsufficient to dissolve a substantial amount of the crystalline sugaradded to the extruder 10.

The crystalline sugar added in the second stage mixing device 100 isadvantageous in providing a tender texture for the final product.Moreover, the bulk of the crystalline sugar added in the second stagemixing device 100 is not heat treated which enables the attainment of ahigher product temperature for the ingredients which are input throughthe dry ingredient feed port 30 (or 30') of the extruder 10 andsubjected to heat treatment for a given throughput rate forsubstantially the entire length of the extruder 10. The crystallinesugar in the second stage mixing device 100 is also relatively cool andprovides a cooling mass to the heat treated ingredients to lower thetemperature of the ingredients just prior to the input of the addedwater through the liquid feed port 200 and thereby reduce thepossibility of oil separation upon the introduction and mixing of theadded water.

The flour may be replaced in whole or in part by flour substitutes orbulking agents including bran. Other ingredients may also be added tothe formulation such as emulsifiers, sources of protein, a leaveningagent and other ingredients conventionally employed in cookies. Heatsensitive ingredients and particulate ingredients may also be addeddownstream from the heat treatment and vigorous mixing zones of theextruder. If aspartame is added, a bulking agent such as a grain brancan be used to replace all or a portion of the crystalline sugar. Sugarin liquid form or other sweeteners may also be used with or in place ofthe crystalline sugar.

The following are examples of the operation of the extruder and secondstage mixing device built in accordance with the present invention andoperated to mix and heat treat a dough formulation having a cookie-likecrumb structure upon final baking.

EXAMPLE I

The below listed ingredients may be fed to the extruder 10 andcontinuous mixer 100 (FIG. 7) to provide a product formulation havingthe final percentages by weight of the output product (including whereeach ingredient is fed to the extruder and/or continuous mixer):

    ______________________________________                                                      % wt of Final                                                   Formulation Mix                                                                             Output Product                                                                              Addition                                          ______________________________________                                        Wheat flour,  50.19%        extruder                                          bleached (about 12%         dry feed port 30                                  by weight water)                                                              Non-fat Dry Milk                                                                            1.51%         extruder                                          (about 52% by weight        dry feed port 30                                  lactose)                                                                      Salt          0.75%         extruder                                                                      dry feed port 30                                  White sugar (sucrose),                                                                      15.82%        continuous mixer                                  granulated                  dry inlet port                                                                101                                               Brown sugar (about                                                                          7.38%         continuous mixer                                  89% sucrose, 3% invert,     dry inlet port                                    4% non-sugar solids         101                                               3% water)                                                                     Soybean spray oil                                                                           22.53%        extruder                                                                      liquid feed port                                                              32                                                Tap Water     0.81%         continuous mixer                                                              liquid feed port                                                              200                                               Sodium bicarbonate                                                                          1.01%         continuous mixer                                                              dry inlet feed                                                                port 101                                          ______________________________________                                    

The extruder may comprise a Werner & Pfleiderer ZSK-57 extruderincluding twelve barrel sections, each including a heating element andcooling means, and twin screws, each having a screw configurationaccording to the invention, as illustrated in FIG. 6. The extruder mayalso be arranged to have upstream dry ingredient and liquid feed ports30', 32' as described above.

The first barrel 11', which contains the first dry feed port 30', may beset on constant cool to obtain an actual barrel temperature of less thanabout 100° F. The remaining eleven barrels may be divided into 7separately measured barrel temperature zones. Barrels 12' and 13'correspond to temperature zone 1, barrel 14' corresponds to zone 2,barrels 15' and 16' correspond to zone 3, barrel 17' corresponds totemperature zone 4, barrel 18' corresponds to temperature zone 5,barrels 19' and 20' correspond to zone 6 and barrels 21' and 22'corresponded to zone 7. Barrels 12' through 22' may be set to heat to300° F. As illustrated in FIG. 2, temperature probes TB and Tp may beinserted into the various barrel sections of the temperture zones tomeasure barrel temperature and product temperature, respectively.

A microwave applicator may be provided as a continuation of the screwchannel of the extruder to apply microwave energy to the ingredientsafter the treatment in the extruder and prior to input into the 2ndstage mixing device. The residence of the ingredients within themicrowave applicator may be approximately 5-20 seconds to raise thetemperature of the ingredients by approximately up to 200° F.

The ingredients may be treated at temperatures above the minimumgelatinization temperature of the starch (assuming that a sufficientamount of water was available for reaction with the starch) but no orsubstantially no gelatinization (measured by differential scanningcalorimetry) should occurr. It is believed that the oil willsufficiently coat the starch containing flour particles to preventsubstantial penetration of moisture into the starch granules so as toavoid substantial gelatinization.

The continuous mixer may compris a twin screw Werner and PfleidererZPM-120 equipped with a screw configuration as illustrated in FIG. 7.The continuous mixer may have three barrel sections 600-602 fastenedend-to-end, each provided with external jacketed heating and coolingmeans. The dry feed port may be set up at barrel 600 of the mixer andmay be opened to the atmosphere. The liquid feed port 200 may be thesame as the dry feed port 101 at barrel 600. The added water feed inletpipe may be inserted into the open port at barrel 600 so that the dryfeed ingredients and the liquid feed ingredients, i.e. tap water, areseparately fed into the same open port.

An additional dry feed port 122, open to the atmosphere, may be formedin barrel 602 for input of shear sensitive and/or heat sensitiveingredients such as particulate ingredients, e.g., nuts, chocolate chipsetc. The screw sections 617, 618 below the dry feed port 122 increasethe speed of conveyance of the ingredients which decreases the degree offill and facilitates the intake and mixing of particulate materials bythe kneading blocks in barrel 602.

The extruder screws 24', 25' may be rotated at about 130 rpm at about 1%of maximum torque. The mixer screws may be rotated at about 60 rpm atabout 19% of maximum torque. The ingredients may be fed in theirrelative amounts to provide a throughput or mass flow rate of thedough-like mixture extrudate from the continuous mixer of about 297lbs/hrs.

The flour, non-fat dry milk and salt may be prepared by mixing theseingredients to obtain a substantially homogeneous dry blend. The dryblend may be continuously fed to the dry feed port 30' of the extruder10. The white and brown sugar may be prepared by mixing the sugaringredients to obtain a second substantially homogeneous dry blend whichmay be continuously fed downstream to the inlet dry feed port 101 of thecontinuous mixer. The oil may be prepared by melting semi-solid soybeanspray oil to obtain a liquid oil which may be continuously fed to theliquid feed port 32' of the extruder. Tap water may be continuously fedto the liquid feed port 200 of the continuous mixer. The sodiumbicarbonate may be continuously fed to the dry feed port 101 of thecontinuous mixer.

On a calculated basis, the water content of the dough-like mixtureformed in the continuous mixer should be about 7.1% by weight, basedupon the total weight of the dough-like mixture.

At steady state, the barrel set temperatures for the extruder should be:

    ______________________________________                                                     Barrel Set                                                       Barrel #     Temperature, °F.                                          ______________________________________                                        11'          cool                                                             12'          300                                                              13'          300                                                              14'          300                                                              15'          300                                                              16'          300                                                              17'          300                                                              18'          300                                                              19'          300                                                              20'          300                                                              21'          300                                                              22'          300                                                              ______________________________________                                    

Tap water may be passed through the cooling jackets of the barrels ofthe continuous mixer to cool the heat treated mass from the extruderwhile admixing it with the other ingredients fed to the continuousmixer.

The pressure in the extruder and in the continuous mixer should be lessthan about 10 bars. The average or median residence time of theingredients heated in the extruder should be about 60-90 seconds. Theaverage or median residence time of the ingredients in the continuousmixer from the second feed ports should be about 60 to 180 seconds.

The heat treated mass formed in the extruder may be extruded without adie to obtain a slurry-like substantially homogeneous heat treated mass.The heat treated mass may be permitted to fall into the dry ingredientfeed port of the continuous mixer. The extrudate temperature uponexiting the extruder should be about 201° F. The substantiallyhomogeneous dough-like mixture formed in the continuous mixer may beextruded from the mixer without a die to obtain a substantiallyunleavened extrudate. The dough-like mixture upon exiting the continuousmixer should have a temperature of about 130° F. The dough-like mixturemay be immediately transferred to an auger fed wire-cutting machine andcut into pieces while hot. The diameter of each of the pieces should beabout 1 inch.

Eight pieces may be subjected to further microwaving in a microwave ovenfor about 70 seconds to produce distinctly leavened cookies. The cookiesshould be browned and havw a crumb-like structure and crumb-liketexture.

What is claimed is:
 1. An apparatus for producing a product having acookie-like crumb structure, which comprisesan extruder including ahousing having a screw channel formed along the longitudinal axis of thehousing; at least one screw-type element rotatably received within thescrew channel to convey and mix ingredients; a feed port means arrangedin the housing adjacent the upstream end thereof to input ingredientsinto the screw channel for conveyance and mixing by the screw-typeelement; means for inputting at least certain ingredients of acookie-like dough formulation, including oil and flour, with less than apreselected total water content, by weight, of the ingredients; themeans for inputting being coupled to the feed port means; a vigorousmixing zone formed by the screw channel and screw-type elementdownstream from the feed port means to vigorously mix and convey theingredients input into the feed port means; a temperature control meansoperating to elevate the temperature of the screw channel for heattreatment of the ingredients input into the feed port means in a heattreatment zone of the housing extending downstream from the feed portmeans; a microwave applicator arranged downstream from the heattreatment zone and vigorous mixing zone of the extruder for further heattreatment of the ingredients input into the feed port means of theextruder; a second stage mixing apparatus including an inlet portcoupled to the downstream end of the extruder housing to receive, mixand convey the heat treated ingredients conveyed through the extruder;an added water inlet port arranged in the second stage mixing apparatus;a source of water coupled to the added water inlet port to add apreselected amount of water through the added water inlet port toincrease the water content and modify the consistency of the heattreated ingredients from the extruder input into the inlet port of thesecond stage mixing apparatus; a mixing zone formed by the second stagemixing apparatus and operating to mix the added water throughout theheat treated ingredients under pressure and temperature conditions toavoid substantial oil separation from the heat treated ingredients andadded water; and an output means at the downstream most end of thesecond stage mixing apparatus.
 2. The apparatus of claim 1 wherein thevigorous mixing zone extends for substantially the entire length of thehousing.
 3. The apparatus of claim 1 wherein the heat treatment zoneextends for substantially the entire length of the housing.
 4. Theapparatus of claim 1 wherein the inlet port and added water inlet portare arranged at the upstream most end of the second stage mixingapparatus.
 5. The apparatus of claim 1 wherein the second stage mixingapparatus comprises an extruder.
 6. The apparatus of claim 1 furthercomprising a downstream dry ingredient feed port in the second stagemixing apparatus.
 7. The apparatus of claim 1 wherein the screw-typeelement comprises a sequence of elements including, in downstream order,a shuffle kneader, an alternating sequence of screw elements and igelelements followed by an alternating sequence of screw elements andkneading block elements, the sequence of elements operating tovigorously mix and convey the ingredients input through the feed portmeans, prior to input of the added water in the second stage mixingapparatus, the sequence of elements together with the screw channelcomprising the vigorous mixing zone.
 8. The apparatus of claim 7,wherein the second stage mixing apparatus includes at least onescrew-type element which comprises a sequence of elements including, indownstream order, an alternating sequence of screw elements and kneadingelements to mix and convey the ingredients input into the second stagemixing apparatus at low pressure and low temperature, relative to thevigorous mixing and heat treatment zones of the extruder.
 9. Theapparatus of claim 1 wherein the feed port means of the extrudercomprises a dry ingredient feed port adjacent to a liquid feed port. 10.The apparatus of claim 1 wherein the extruder comprises a twin-screwextruder.
 11. The apparatus of claim 1 wherein the second stage mixingapparatus comprises a continuous mixer.
 12. The apparatus of claim 11wherein the continuous mixer comprises a twin screw continuous mixer.13. The apparatus of claim 1 further comprising a means for inputtingcrystalline sugar coupled to the inlet feed port of the second stagemixing apparatus.
 14. The apparatus of claim 13 wherein a screw-typeelement of the second stage mixing apparatus forms a high speedconveyance zone beneath the inlet feed port of the second stage mixingapparatus for rapid intake of the crystalline sugar into the continuousmixing apparatus.
 15. The apparatus of claim 1 wherein the temperaturecontrol means comprises an electric heating element means arranged inthe housing to apply heat to the screw channel.
 16. The apparatus ofclaim 15 wherein the temperature control means further comprises acooling water flow means arranged around the screw channel to reduce thetemperature of the screw channel.
 17. The apparatus of claim 16 whereinthe temperature control means includes a thermostat control toselectively activate the electric heating element means and coolingwater flow means to control the temperature of the screw channel.
 18. Atwo-stage mixing apparatus which comprises:a housing including a screwchannel formed along the longitudinal axis of the housing; at least onescrew-type element rotatably received in the screw channel forconveyance and mixing of ingredients; a feed port means arranged in thehousing at the upstream end thereof to input ingredients into the screwchannel for conveyance and mixing by the screw-type element; atemperature control means operating to elevate the temperature of thescrew channel along a preselected portion of the screw channel; thescrew-type element being configured to provide a vigorous mixing andconveying action on ingredients input through the feed port means; amicrowave applicator arranged downstream from the heat treatment zoneand vigorous mixing zone of the extruder for further heat treatment ofthe ingredients input into the feed port means of the extruder; thehousing having an output means; a second stage mixing apparatus coupledto the output means to receive ingredients from the housing; an addedwater inlet port arranged in the second stage mixing apparatus; a sourceof water coupled to the added water inlet port; and the second stagemixing apparatus operating to apply a gentle mixing and conveying to theingredients received from the housing and the added water.